1. Field of the Invention
The present invention generally relates to a patch for transdermal drug delivery and method of manufacturing the same, in particular to an embeddable micro-needle patch for transdermal drug delivery having biodegradable polymeric materials and method of manufacturing the same.
2. Description of the Related Art
In current drug therapy paths, oral administration and hypodermic injection are the most frequently seen methods, wherein oral administration is convenient and easily obtained to become the main manner of drug therapy. However, many oral medicines are firstly decomposed in gastrointestinal system and then enter into blood circulation systems to generate treatment effect by the first-pass metabolism effect of the liver. The treatment effect is unable to be precisely controlled since the foregoing progress is too long and may be influenced by the effect of digestive system. In addition, hypodermic injection is an invasive treatment. Patients may feel more painful during the injection, and the needle head and the wound may be infected to cause safety concerns.
The transdermal drug delivery system is a novel drug therapy path capable of overcoming the defect of the foregoing two manners of drug therapy. It does not only prevent the drug efficacy of oral medicines from losing due to the digestion of gastrointestinal system but also reduces pain and infection caused by hypodermic injection. However, the outermost layer of human skin is stratum corneum that is a very important protection barrier for human bodies and belonging to hydrophobicity and having negative charges. Consequently, macro-molecular drugs and hydrophilic drugs are difficult to penetrate through to cause the serious barrier in developing the transdermal drug delivery system.
To overcome the foregoing problem, a technique of combining a conventional needle treatment with the transdermal patch is recently developed. The technique is composed of a patch fully distributed with micro-needles. These micro-needles can directly penetrate through stratum corneum of skin to effectively deliver macro-molecular drugs and hydrophilic drugs, such as vaccines, proteins, insulin or DNA (deoxyribonucleic acid), that are difficult to pass through skin to epidermis of skin. These drugs then enter the body via blood circulation after absorbing by distal micro vascular, thereby achieving treatment effect.
However, the micro-needle patch sale in markets is usually made of metal materials or silicon materials. The user must take the infection risk probably caused by broken micro-needles or repeatedly using micro-needles. These micro-needle patches may also cause the danger of medical waste and need to be in touch with skin for long time to cause allergic reaction such as skin pruritus and red and swollen. In addition, the currently developed micro-needle patch usually belongs to the formula of rapidly releasing drugs. It does not have the prolonged action formula capable of continuously releasing the drugs. Therefore, improving micro-needle materials, structures, and usage manner, and controlling time of releasing the drugs from the patch for transdermal drug delivery are an important issue of researching and developing the patch for transdermal drug delivery system.